1. Technical Field
This disclosure relates generally to telephone number identification.
2. Description of the Related Art
It is known to provide a web-based hosted (“platform-as-a-service”) solution through which business entities create and manage interactive or notification communications campaigns. An example of an interactive communications campaign is a telephone campaign to determine whether a target recipient desires to transfer a credit card balance to a new account, a campaign to remind a recipient that a credit card payment is due and to offer the recipient an opportunity to speak with a customer representative concerning any payment issues, or the like. The hosted solution typically is implemented as an application (or “managed”) service provider. One or more business entities (“clients”) that desire to use the service typically register and access the service through an on-line (e.g., web-based) portal. In one representative use scenario, the managed service provider entity provides outbound telemarketing services on behalf of participating clients. The campaign typically is provisioned by the client. Thus, for example, using a web-based interface, a participating client defines a script for the campaign, imports a set of contacts, and defines one or more parameters that govern how the campaign is to be run. At a designated time, the service provider initiates the campaign, e.g., by providing the contacts to a set of telephone servers that set-up and manage the telephone calls to the targets of the campaign. During a given outbound call, as noted above, a recipient (a “customer”) may be afforded an option to connect to a contact center, e.g., to speak to a customer representative, typically by entering a digit on a keypad.
Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and a telephone switching center. A DTMF keypad (typically corresponding to the buttons on a phone) is laid out in a 4×4 matrix, with each row representing a low frequency, and each column representing a high frequency. DTMF tones are generated by combining two tones each of different frequency, which occurs when a user presses a digit in the keypad. In conventional TDM-based telephone systems, DTMF tones can be heard in any conversation or audio recording on the line. As such, the tones are sometimes referred to as in-band signaling because the same channel used to send the voice conversation is also used for the signaling tones.
Voice over IP (VoIP, or voice over Internet Protocol) commonly refers to the communication protocols, technologies, methodologies, and transmission techniques involved in the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. Communications over VoIP are typically a continuous stream of data packets that are delivered via a low level communication protocol called RTP (Real-Time Transport Protocol). VoIP calls also conform (at a higher communication layer) to the Session Initiation Protocol (SIP). Because SIP does its signaling over Internet Protocol (IP)-based networks as packet data, it is not necessary to have in-band transmission of DTMF tones. Instead, SIP calls transmit key presses during the call as “out-of-band events.” There are several known methods for transmitting DTMF in SIP networks: RFC 2833, SIP INFO (RFC 2976), and in-band. RFC 2833 defines a special packet that includes a payload format for carrying DTMF digits. When a provider such as described above integrates with a VoIP carrier, the provider must be able to distinguish when a customer has pressed a “digit” on a keypad, irrespective of whether that customer is connected through a conventional TDM system or through VoIP. Typically, there are multiple ways to detect whether the customer has pressed a digit (to generate DTMF signaling). As noted above, that signaling may be received and passed through to the service provider as in-band signaling, or it may be passed through to the provider as an RTP payload, per RFC 2833, or (more commonly), both types of signaling may occur at the same time (over the same connection). When a service provider integrates with the carrier, theoretically the carrier provides an indication of how such digits are expected to be passed. In practice, however, the carrier may not send the digits in the manner that has been negotiated. Or, when the service provider works with multiple carriers, the various carriers may operate with different implementations and/or interpretations of the standards may apply to the signaling. As such, it is often the case that the provider receives signaling or other information representative of DTMF digits but cannot distinguish the true nature of the customer's action.